Radar technologies can utilize pulse modulation to achieve wide bandwidths for fine range resolution in conjunction with long pulses duration to enhance pulse energy and hence enhance signal to noise ratio (SNR) for both transmitted and received signals.
To achieve finer signal resolutions, radar signal technologies are being developed that utilize ever larger bandwidths. Radar frequency bands are chosen to facilitate some advantage to an immediate mission, such as foliage or ground penetration at the lower frequencies (e.g., ultra high frequency (UHF), very high frequency (VHF), and lower) through to long-range operation in adverse weather at lower microwave frequencies, to ultra-fine resolutions and narrow antenna beams at frequencies corresponding to a millimeter wavelength.
As the necessary operational bandwidth increases, particularly at the lower frequencies, a radar signal may have to compete with other spectrum users for any required frequency bands and sub-bands. Such competition can be manifested as interference, whereby a radar system can act as both an offender and a victim, depending on the nature of the interference.
Regulatory limits can be in place to prohibit a radar system from transmitting in one or more specific spectral regions, which in turn can limit operation of the radar system.